feat: DX RATING calculation

sdgb-api/Cargo.toml

@@ -44,3 +44,7 @@ bincode = { version = "2.0.1", optional = true }
 # magic macro
 crabtime = { git = "https://github.com/wdanilo/crabtime.git", rev = "2ed856f5" }
 rustc-hash = "2.1.1"
+rust_decimal = { version = "1.37.2", default-features = false, features = [
+    "serde-with-arbitrary-precision",
+    "macros",
+] }

sdgb-api/src/helper/mod.rs

@@ -11,4 +11,4 @@ pub fn level_name(level: u32) -> &'static str {
 }
 
 mod music_db;
-pub use music_db::{MUSIC_DB, MusicInfo,};
+pub use music_db::{Level, MUSIC_DB, MusicInfo};

sdgb-api/src/helper/music_db/mod.rs

@@ -1,15 +1,26 @@
 use std::{fs::OpenOptions, sync::LazyLock};
 
+use rust_decimal::{Decimal, dec, serde::DecimalFromString};
 use rustc_hash::FxHashMap;
-use serde::{Deserialize, Serialize};
+use serde::Deserialize;
 use spdlog::{info, warn};
 
-#[derive(Default, Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[derive(Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct MusicInfo {
     pub id: u32,
     pub name: String,
     pub version: i64,
+    pub levels: Vec<Level>,
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct Level {
+    /// 0, 1, 2, 3, 4, 5
+    pub level: u32,
+    /// for example: "13.7"
+    pub difficulty: DecimalFromString,
 }
 
 type MusicDB = FxHashMap<u32, MusicInfo>;
@@ -30,3 +41,65 @@ pub static MUSIC_DB: LazyLock<Option<MusicDB>> = LazyLock::new(|| {
 
     Some(db.into_iter().map(|entry| (entry.id, entry)).collect())
 });
+
+impl Level {
+    /// achievement: xxx.xxxx% * 10000
+    ///
+    /// This will **NOT** ignore utage level, you can calculate a in-theory DX Rating.
+    ///
+    /// On invalid input, it returns 0.
+    pub fn dx_rating(&self, achievement: i32) -> u32 {
+        let achievement = Decimal::new(achievement as _, 4);
+        let difficulty_rank: Decimal = self.difficulty.value;
+
+        let factor = match () {
+            // larger than best achievement
+            _ if achievement >= dec!(101.0) => return 0,
+
+            _ if achievement >= SSS_PLUS_THRESHOLD => SSS_PLUS_FACTOR,
+            _ if achievement >= SSS_THRESHOLD => SSS_FACTOR,
+            _ if achievement >= SS_PLUS_THRESHOLD => SS_PLUS_FACTOR,
+            _ if achievement >= SS_THRESHOLD => SS_FACTOR,
+            _ if achievement >= S_PLUS_THRESHOLD => S_PLUS_FACTOR,
+            _ if achievement >= S_THRESHOLD => S_FACTOR,
+            _ if achievement >= AAA_THRESHOLD => AAA_FACTOR,
+            _ if achievement >= AA_THRESHOLD => AA_FACTOR,
+            _ if achievement >= A_THRESHOLD => A_FACTOR,
+
+            // lower than A rank, does not get rating.
+            _ => return 0,
+        };
+
+        (factor * difficulty_rank * achievement)
+            .floor()
+            .try_into()
+            .unwrap_or_default()
+    }
+}
+
+const SSS_PLUS_THRESHOLD: Decimal = dec!(100.5);
+const SSS_PLUS_FACTOR: Decimal = dec!(0.224);
+
+const SSS_THRESHOLD: Decimal = dec!(100);
+const SSS_FACTOR: Decimal = dec!(0.216);
+
+const SS_PLUS_THRESHOLD: Decimal = dec!(99.5);
+const SS_PLUS_FACTOR: Decimal = dec!(0.211);
+
+const SS_THRESHOLD: Decimal = dec!(99);
+const SS_FACTOR: Decimal = dec!(0.208);
+
+const S_PLUS_THRESHOLD: Decimal = dec!(98);
+const S_PLUS_FACTOR: Decimal = dec!(0.203);
+
+const S_THRESHOLD: Decimal = dec!(97);
+const S_FACTOR: Decimal = dec!(0.2);
+
+const AAA_THRESHOLD: Decimal = dec!(94);
+const AAA_FACTOR: Decimal = dec!(0.168);
+
+const AA_THRESHOLD: Decimal = dec!(90);
+const AA_FACTOR: Decimal = dec!(0.152);
+
+const A_THRESHOLD: Decimal = dec!(80);
+const A_FACTOR: Decimal = dec!(0.136);

sdgb-api/src/title/model/get_user_rating_api/mod.rs

@@ -40,8 +40,6 @@ pub struct UserRating {
 pub struct MusicRating {
     /// Maimai music id
     pub music_id: u32,
-    /// difficulty
-    ///
     /// - 0: BASIC
     /// - 1: ADVANCED
     /// - 2: EXPERT
@@ -92,17 +90,28 @@ pub struct Udemae {
 
 impl Display for GetUserRatingApiResp {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let b35 = &self.user_rating.rating_list;
+        let b15 = &self.user_rating.new_rating_list;
         f.write_fmt(format_args!("用户ID: {}\n", self.user_id))?;
 
-        f.write_str("\n---------- B35 ----------\n")?;
-        for b35 in &self.user_rating.rating_list {
-            f.write_fmt(format_args!("{b35}\n---\n"))?;
+        f.write_str("\n---------  B35  ---------\n")?;
+        for music in b35 {
+            f.write_fmt(format_args!("{music}\n---\n"))?;
         }
 
-        f.write_str("\n---------- B15 ----------\n")?;
-        for b15 in &self.user_rating.new_rating_list {
-            f.write_fmt(format_args!("{b15}\n---\n"))?;
+        f.write_str("\n---------  B15  ---------\n")?;
+        for music in b15 {
+            f.write_fmt(format_args!("{music}\n---\n"))?;
         }
+
+        let b35_rating: u32 = b35.iter().filter_map(|m| m.dx_rating()).sum();
+        let b15_rating: u32 = b15.iter().filter_map(|m| m.dx_rating()).sum();
+
+        f.write_str("\n--------- Total ---------\n")?;
+        f.write_fmt(format_args!("B35 Rating: {b35_rating}\n"))?;
+        f.write_fmt(format_args!("B15 Rating: {b15_rating}\n"))?;
+        f.write_fmt(format_args!("总 Rating: {}\n", b35_rating + b15_rating))?;
+
         Ok(())
     }
 }
@@ -110,10 +119,11 @@ impl Display for GetUserRatingApiResp {
 impl Display for MusicRating {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         f.write_fmt(format_args!("歌曲ID: \t{}\n", self.music_id))?;
-        if let Some(info) = MUSIC_DB.as_ref().map(|db| db.get(&self.music_id)).flatten() {
-            let title = &info.name;
+
+        if let Some(title) = self.music_title() {
             f.write_fmt(format_args!("曲目标题: \t{title}\n"))?;
         }
+
         f.write_fmt(format_args!(
             "谱面版本: \t{}\n",
             match (self.music_id / 10000) % 10 {
@@ -125,11 +135,36 @@ impl Display for MusicRating {
 
         f.write_fmt(format_args!("游玩难度: \t{}\n", level_name(self.level)))?;
         f.write_fmt(format_args!(
-            "达成率: \t{}.{:04}%",
+            "达成率: \t{}.{:04}%\n",
             self.achievement / 10000,
             self.achievement % 10000
         ))?;
 
+        if let Some(dx_rating) = self.dx_rating() {
+            f.write_fmt(format_args!("DX RATING: \t{dx_rating}"))?;
+        }
+
         Ok(())
     }
 }
+
+impl MusicRating {
+    pub fn music_title(&self) -> Option<String> {
+        MUSIC_DB
+            .as_ref()?
+            .get(&self.music_id)
+            .map(|music_info| music_info.name.clone())
+    }
+
+    pub fn dx_rating(&self) -> Option<u32> {
+        Some(
+            MUSIC_DB
+                .as_ref()?
+                .get(&self.music_id)?
+                .levels
+                .iter()
+                .find(|d| d.level == self.level)?
+                .dx_rating(self.achievement),
+        )
+    }
+}